The present invention relates to a cutting insert for the turning of grooves and parting operations. In particular the cutting insert, according to the invention, is suitable for the turning of grooves, although it also can be used for different axial grooving and parting operations, as well as for axial and radial longitudinal turning.
In such machining operations, chip breaking and chip forming are frequently of decisive importance for undisturbed output. Modern, high productive machines are very dependent on good chip transport. Long, uncontrollable chips can easily cause machine interruptions and rejection of parts. Chip control must therefore be given high priority and it governs, to a high degree, the tool design.
Cutting inserts intended for grooving operations and parting are usually clamped in a holder, which is blade shaped in order to fit into the slot produced in a workpiece. Such cutting inserts are for example known from U.S. Pat. No. 4,778,311, U.S. Pat. No. 4,992,008, U.S. Pat. No. 5,135,336 and U.S. Pat. No. 5,423,639. At the same time there is nowadays a requirement to, if possible, obtain an improved surface finish of the surfaces in the slots produced. A first purpose of the invention is to produce a cutting insert, which is well suited to give improved surface finish of the surfaces in the slot produced in a work piece.
It is another purpose of the present invention to provide a cutting insert, which is well suited for repeated radial grooving as well as longitudinal turning.
It is a third purpose of the present invention to produce a cutting insert which gives advantages from a pressing technology point of view during insert manufacture because portions with large radii give a more even compacting result, especially in the production of more difficult-to-press material such as cermets.
It is a fourth purpose of the present invention to produce a double-ended cutting insert the clearance surface of which, below the main cutting edge, will serve as an axial stop surface, whereby the design thereof is optimized such that the insert is suitably protected during continuous chip forming machining.
These other purposes have been achieved by a cutting insert for grooving by a double-ended metal cutting insert which comprises a body that includes an upper surface, a bottom surface, two mutually parallel side surfaces each extending between the upper and bottom surfaces, first and second end surfaces disposed at respective axial ends of the body, and a groove formed in the bottom surface. The groove includes a central concave portion and two support surfaces extending downwardly from respective sides of the concave portion. The support surfaces diverge in a downward direction. An intersection between the upper surface and the first and second end surfaces form first and second cutting edges, respectively. Each of the first and second end surfaces includes an upper portion connected to a respective one of the first and second cutting edges, and a lower portion connected to the upper portion by a concave transition portion, wherein the lower portion is recessed axially inwardly relative to the upper portion. The lower portion is oriented perpendicular to the bottom surface.